EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2023-1415 Towards a mechanistic description of autoxidation chemistry: from precursors to atmospheric implications Pichelstorfer Lukas https://orcid.org/0000-0001-9470-257X 1 2 3 Roldin Pontus 4 Rissanen Matti https://orcid.org/0000-0003-0463-8098 5 6 Hyttinen Noora https://orcid.org/0000-0002-6025-5959 7 Garmash Olga https://orcid.org/0000-0002-9675-3271 5 8 Xavier Carlton https://orcid.org/0000-0001-8120-0431 3 4 9 Zhou Putian https://orcid.org/0000-0003-0803-7337 3 Clusius Petri 3 Foreback Benjamin https://orcid.org/0000-0002-5061-7098 3 Golin Almeida Thomas https://orcid.org/0000-0002-1794-1507 3 6 Deng Chenjuan 10 Baykara Metin 3 11 Kurten Theo 6 Boy Michael 3 12 pi-numerics, Neumarkt am W., 5202, Austria Chemistry and Physics of Materials, University of Salzburg, A-5020, Austria Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, 00560 Helsinki, Finland Division of Nuclear Physics, Department of Physics, Lund University, P. O. Box 118, 221 00 Lund, Sweden Aerosol Physics Laboratory, Tampere University, 33720 Tampere, Finland Department of Chemistry, University of Helsinki, 00014 Helsinki, Finland Department of Chemistry, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä, Finland Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA SMHI / Swedish Meteorological and Hydrological Institute Research Department, Unit of Meteorology/Environment and Climate, SE - 601 76 NORRKÖPING State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, 100084 Beijing, China Climate and Marine Sciences Department, Eurasia Institute of Earth Sciences, Istanbul Technical University, Maslak, Istanbul, 34469, Turkey School of Engineering Science, Lappeenranta-Lahti University of Technology, 53851 Lappeenranta, Finland 26 07 2023 2023 1 30 Copyright: © 2023 Lukas Pichelstorfer et al. 2023 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1415/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1415/egusphere-2023-1415.pdf

<p>In the last decades, atmospheric formation of secondary organic aerosol (SOA) gained increasing attention due to its impact on air quality and climate. However, methods to predict its abundance are mainly empirical and may fail at real atmospheric conditions. In this work, a close-to mechanistic approach allowing SOA quantification is presented, with focus on a chain-like chemical reaction called &ldquo;autoxidation&rdquo;. A novel framework is employed to a) describe the gas-phase chemistry, b) predict the products&rsquo; molecular structures and c) explore the contribution of autoxidation chemistry on SOA formation under various conditions. As a proof of concept, the method is applied to benzene, an important anthropogenic SOA precursor.</p> <p>Our results suggest autoxidation to explain up to 100 % of the benzene-SOA formed under low-NOx laboratory conditions. While under atmospheric-like day-time conditions, the calculated aerosol mass continuously increases, as expected based on prior work. Additionally, a prompt increase, driven by the NO<sub>3</sub> radical, is predicted at dawn. This increase has not yet been observed experimentally and questions the applicability of the widely accepted concept of OH-based SOA mass yield in the atmosphere.</p>